When several armed robberies occurred recently in Lancaster, Calif., police had little of use on the two suspects. Then, a reliable image of one suspect turned up from a surveillance camera.

In years past, that still might not have been enough for the Los Angeles County Sheriff’s Department to close the case.

But with the help of new facial recognition software, investigators plugged the image into a database of booking photos and quickly came up with a possible match. That led to a pair of arrests on Jan. 27.